Gwyneth Paltrow and Robert Downey Jr. of ‘Iron Man 3’ An iron-clad relationship

There’s something of the old married couple about Gwyneth Paltrow and Robert Downey Jr., though they’re married to other people.

They’ve known each other for 20 years, through bad times (his) and good (hers all along and now his, too). They’re cozy and comfy sitting down together for an interview, shifting easily between talking about their Marvel Studios superhero sequel “Iron Man 3,” chatting up each other’s career and family and trading small talk about their little ailments as Downey rummages through a case of nostrums he travels with.

“Travel’s tough when you’re not a kid anymore,” Downey adds. “You’ve got to take it really seriously.”

Both are taking everything seriously now, from work to family to lifestyle. Downey and Paltrow are in enviable places among their forty-something Hollywood peers.

At 48, he’s the great reclamation project of show business, rebounding from a fitful early career over- shadowed by drug abuse and prison to become arguably the hottest leading man on the planet. “Iron Man 3” just opened to a whopping $195 million overseas, surpassing last year’s international debut of Marvel’s “The Avengers,” in which he also had the leading role.

At 40, Paltrow’s diversified into a super-hyphenate. While slowing down on acting to raise her two children with her husband, Coldplay singer Chris Martin, Paltrow has just published her second cookbook, runs the lifestyles website Goop.com and is a business partner with fitness trainer Tracy Anderson. Paltrow also managed to book-end her Academy Award for “Shakespeare in Love” with an Emmy win for her guest spots on “Glee.”

Paltrow has plenty of detractors, though. Critics questioned her designation by People magazine as the world’s most-beautiful woman, which came days after Star magazine named her the most-hated celebrity.

Downey and Paltrow are following “Iron Man 3” with smaller dramas, Paltrow starring opposite Antonio Banderas in the Pablo Picasso tale “33 Dias,” Downey joining Robert Duvall for the father-son story “The Judge.” He also has plans for a third entry in his other franchise, “Sherlock Holmes,” though the future of “Iron Man,” Downey’s billionaire genius Tony Stark and Paltrow’s Gal-Friday-turned-girlfriend-and-CEO Pepper Potts are uncertain.

“Iron Man 3” hints that Tony might hang up his metal suits to focus on life with Pepper. Downey won’t tip his hand on the prospects of future solo entries or whether he’ll return for the upcoming “The Avengers” sequel. After so many years on the outs in Hollywood, though, Downey’s gotten used to the blockbuster life.

Paltrow eagerly says she would come back for more “Iron Man.” Especially now that she’s getting into the thick of things.

In “Iron Man 3,” Pepper graduates from glorified personal assistant to running Tony’s empire, and Paltrow even gets to put on the Iron Man suit and mix it up in the action scenes.

“I seriously question all my career choices up to that point. It’s like, what have I been doing in these highbrow frigging corset things? This is so much more fun,” Paltrow says.

Paltrow and Downey became friends after meeting at a film festival in the 1990s, though like much of Hollywood, she had doubts about the talented but manic actor who squandered his early promise through his partying and addictions.

“She was out there banging out one hit after the next, and I was locked in a bathroom somewhere. So be it. Life is beautiful,” Downey said.

“And now look,” Paltrow replied.

The once out-of-control Downey looks like a man in complete control now. Backing him up and keeping him honest, much as Pepper steers Tony straight, is his wife and producing partner, Susan Downey.

They have a year-old son, and considering the mess he made of his personal life in his 20s and 30s, Downey’s happiness on the home-front seems an appropriate complement to his career turnaround, which included an Oscar nomination for 2008’s “Tropic Thunder” (he also was nominated for 1992’s “Chaplin”).

Is his future nothing but bliss?

“I see perpetual vainglory,” Downey initially jokes. Then, “I see transitioning into things that are age- and spirit-appropriate, and I couldn’t have imagined that I’d be here five years ago.”